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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-01-13 to 2012-02-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Gudeline study OECD 301 F, GLP. The 10-day-window was not passed.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
adoped July 17, 1992
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Version / remarks:
of May 30, 2008 (EEC Publication No. L 142/496, May 2008)
Principles of method if other than guideline:
The biodegradation of organic compounds is determined by the determination of oxygen consumption of microorganisms using a manometric
respiratory test over a period of 28 days.
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Source of inoculum/activated sludge: Aerobic activated sludge (micro-organisms from a domestic wastewater treatment plant) was supplied by the sewage works of Rossdorf, Germany.
Duration of test (contact time):
28 d
Initial conc.:
102 mg/L
Based on:
ThOD/L
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 21-22 °C
- pH: 7.6 at study start, 6.8 - 7.6 at the end of the test
- pH adjusted: no
- Suspended solids concentration: 1.5 dry material per litre
- Continuous darkness: yes

TEST SYSTEM
- Measuring equipment: BSB Sensomat system, Aqualytic Dortmund, Germany
- Test performed in closed vessels due to significant volatility of test substance: flasks were closed gas-tight
- Details of trap for CO2 and volatile organics if used: aqueous solution of potassium hydroxide (45%) was used for trapping the produced CO2

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes, poisoned with HgCl2 (stock solution of 48.84 mg/mL)
- Toxicity control: Ethyleneglycol dimethacrylate and the reference substance
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
69
Sampling time:
28 d
Remarks on result:
other: 10-d window was not reached
Parameter:
% degradation (O2 consumption)
Value:
30 - 33
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
45
Sampling time:
10 d
Parameter:
% degradation (O2 consumption)
Value:
50 - 53
Sampling time:
15 d
Details on results:
Biodegradation of the reference substance sodium benzoate: Sodium benzoate was sufficiently degraded to 85 % after 14 days and after 28 days of
incubation. Therefore it was concluded that the aerobic activated sludge inoculum used was suitable for the test.

Biodegradation of the toxicity control: Toxicity control containing both, Ethyleneglycol dimethacrylate and the reference substance, 58 % biodegradation was noted within 14 days and 62 % biodegradation after 28 days of incubation.
Ethyleneglycol dimethacrylate was therefore not inhibitory to the aerobic activated sludge micro organisms.
Abiotic control: The oxygen demand in the abiotic control was zero. No correction of the test item degradation rates had to be done.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
A degradation rate of 69 % was obtained after 28 days, thus the test substance Ethylene glycol dimethacrylate has to be classificated as readily
biodegradable, but failing 10-day window.
Executive summary:

In a valid guideline study a degradation rate of 69 % was obtained after 28 days, thus the test substance Ethylene glycol dimethacrylate has to be classificated as readily biodegradable, but failing 10-day window.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study (EEC Dir. 84/449, published in: Official Journal of the European Communities, No. L251/188, Closed Bottle Test), GLP. 10-day-window not reached.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: EEC Dir. 84/449, published in: Official Journal of the European Communities, No. L251/188, Closed Bottle Test
Principles of method if other than guideline:
The biodegradation of organic compounds is determined by the determination of oxygen consumption of microorganisms using closed bottles filled with a mineral nutrient solution and the substance as the only carbon source.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Samples of
microorganisms of a secondary effluent were withdrawn from a sewage plant mainly fed with domestic sewage.
Duration of test (contact time):
28 d
Initial conc.:
2.01 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Value:
71.2
Sampling time:
28 d
Remarks on result:
other: 10-d window was not reached
Parameter:
% degradation (O2 consumption)
Value:
29.3
Sampling time:
5 d
Parameter:
% degradation (O2 consumption)
Value:
31.2
Sampling time:
10 d
Parameter:
% degradation (O2 consumption)
Value:
41.1
Sampling time:
15 d

Oxygen contents and calculations of the degradation rate of the test substance and the reference substance

(table 1):

 days  vessel  O2-Contr (mg/l)  IO-Blind (mg/l)  Test-Substance (mg/l)  Ref-Sub;  Aniline (mg/l)
 0  1  8.5  8.61  8.39  8.58
   2  8.5  8.47  8.40  8.44
 5  1  8.32  8.30  7.17  5.30
   2  8.30   8.31  7.24  5.59
 10  1  8.57  8.54  7.30  5.03
   2  8.54  8.38  7.28  5.08
 15  1  8.27  8.32  6.74  4.94
   2  8.26           8.25  6.75  4.81
 28  1  8.30  8.12  5.42  4.15
   2  8.27  8.07  5.43  3.81

 

O2-Analysis was performed with an oxygen electrode; ThOD: 1.86 mg/mg subst.; Temp.of the dilution water after aeration: 20°C; O2-concentration of the water after aerartion and standing (20hours) before start: 8.61mg/l;  stock solution of the test substance (Ethylene glycol dimethacrylate)250 mg/l; stock solution of the reference substance (Aniline): 100 mg/l; Test procedure: 4 Groups of BOD bottles were prepared: 1 ) air-bubble free with the medium containing the test material (Test-Substance, TS) 2) air-bubble free with the medium containing the reference material (Ref-Substance, Rf) 3) air-bubble free with the medium containing only microorganisms (Io-Bl) 4) air-bubble free with the mineral medium containing the oxygen blanc (O2-Contr). The oxygen was determined at the days 0, 5, 10, 15 and 28 elektochemically (see: table1) (oxygen probe: WTW EO 166; measuring instrument: WTWOXI 550).  For the time in between the measurements the bottles were incubated at 20°C in the dark..
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
In a valid guideline study a degradation rate of 71.2% was obtained after 28 days, thus the test substance Ethylene glycol dimethacrylate has to be classificated as readily biodegradable, but failing 10-day window.
Executive summary:

According to the measured values of O2 -concentrations (in dependance of time, x) in the test vessels (with/without test 

material/inoculum)  via O2 -electrode, was calculated the BODx (Biological Oxygen Demand, in dependance of time, x). Via the BODx,

the ThOD and the concentration of the test substance EGDMA (Ethylene glycol dimethacrylate) in solution, the biotic Degradation at time x was calculated. The 

calculation of Dt, the biodegradation rate in time, was performed according to the following formula: Dt(%) = [(mg BODx /l) : (mg 

Subst / l  x ThOD)] x 100 Description of the curve of biodegradation (%): After a lag phase of about 10 days biodegradation takes 

place. Within the following 10 days, after 10% biodegradation was exceeded, about 40% degradation was obtained.  Finally, a 

degradation rate of 71.2% was obtained. Since degradation time (28 days), belonging to the degradation rate of about > 60%, exceeded 

the 10 days window, Ethylene glycol dimethacrylate has to be classificated according to the criteria of  test evaluation as readily biodegradable, but failing 10-day window.

Description of key information

According to different test guidelines (Screening tests OECD 301 F and OECD 301 D) Ethyleneglycol dimethacrylate was assessed to be readily biodegradable in activated sludge (> 60 % degradation within 28 days) but failing the 10-day window. (Evonik Industries 2012 and 1990).

BIOWIN v4.10 prediction: readily biodegradable.

This is likely due to the kinetics of sequential metabolism since both primary metabolites, Hydroxyethyl methacrylate and methacrylic acid are readily biodegradable acc. OECD criteria. Consequently, it is expected that Ethyleneglycol dimethacrylate will be ultimately biodegraded within 28 days.

Conclusion:

Ethyleneglycol dimethacrylate is assessed to be readily biodegradable, but failing 10-day window. Utimate biogeradation is expected within 28 days.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

Hydroxyethyl methacrylate (CAS 868-77-9) and Methacrylic acid (CAS 79-41-4) are expected to be the primary metabolites of Ethyleneglycol dimethacrylate. Both substances are readily biodegradable acc. OECD criteria. Microbial metabolism simulator of OECD Toolbox version 3.3.0-132 generates in summary of both substances (HEMA and Methacrylic acid) similar metabolites as Ethyleneglycol dimethacrylate itself. This information supports the assumption that EGDMA will be biodegardable utimately wthin 28 days.